During an imposition of excessive loads upon the front of a vehicle, it is desirable that the vehicle's transmission cross-member and frame rails remain connected to one another even if there is relative displacement between the two. Currently, on many vehicles, this desire is met through large deformations of a steel cross-member, which is rigidly affixed to the frame rails.
Also, however, during imposition of these excessive loads, it is desirable to minimize damage to the transmission cross-member in the locations where it attaches to the frame rails. If the transmission cross-member and frame rails are rigidly attached, then the chance of localized damage to these beams is increased.
Further, transmission cross-members can now be made out of a reinforced plastic material in order to reduce weight and reduce the transmission of noises and vibrations from the powertrain of a vehicle into the vehicle frame. In general, plastic cross-members cannot deform as much as steel cross-members, since the plastic material has a lower strain-to-failure limit. Thus, a different mechanism is needed to accommodate displacement caused by excessive loads while still keeping the transmission cross-member connected to the frame rails.
The need arises, therefore, for a mechanism that will allow for relative movement between two interconnecting beams during an excessive loading event while still allowing the two beams to remain attached; and furthermore will reduce the possibility for localized damage to the cross-member, whether made of metal or reinforced plastic.